Boot from RAIDZ in 8.0-BETA3?

[Jason Garrett]

IMHO, unless you have a NEED to do this with the 8-BETA's I would not
attempt. While I had this working in 8.0-BETA1 upon reboot I would loose
data from entire mountpoints on the root pool. First it was /usr/ports, not
a big deal. Then it was /var/db/pkg.. the system had no idea what was
installed and what wasn't. This was a test machine, so no harm, no foul. I
would definatley not recommend this AT ALL.

Just my 2 cents, YMMV, etc.